This invention relates to an apparatus and method for flotation separation and more particularly to an apparatus and method for froth flotation separation and beneficiation of mineral ores and carbonaceous matter.
Froth flotation operates to separate finely ground valuable minerals from their associated gangue. In general, the frothing process is carried out by introducing air into a pulp or slurry of finely divided mineral ore or other matter desired to be floated in water containing a frothing or foaming agent whereby a froth is formed. The particulate mineral matter with a specific affinity for air bubbles rises to the surface in the froth and is thus separated from the gangue wetted by the water.
Conventional prior art processes for froth flotation separation of a slurry or pulp of particulate matter typically include those processes based on constructions wherein air is introduced into the liquid slurry or pulp of the particulate matter as, e.g., through a porous cell bottom or a hollow impeller shaft, thereby producing a surface froth.
Improved methods and apparatus for carrying out froth flotation separation of coal and other minerals are disclosed in U.S. Pat. No. 4,347,126 and U.S. Pat. No. 4,347,127. These patents disclose a flotation apparatus wherein a primary feed spray nozzle is positioned above the flotation tank for spraying input slurry, such as particulate coal or mineral ore, into the tank and a recycle spray nozzle is positioned above the tank for respraying particulate matter collected in a collection trough positioned in the tank for collecting sinking material. In this apparatus, the particles collected in the trough are recycled and a portion of the recycled particulates float as a froth on the water surface an additional time and are recovered. In the apparatus of U.S. Pat. No. 4,347,127, the recycled spray nozzle is positioned in proximity to the primary feed spray nozzle and a vertical baffle plate is positioned in the tank to provide separation for materials sinking from the sprays of the respective nozzles.
While the apparatus of U.S. Pat. No. 4,347,127 provides for good yields of beneficiated product, improvements in the apparatus are desired For example, the collection means for collecting sinking material, i.e., the collection trough, in said U.S. Pat. No. 4,347,127 has not proven to be an efficient means for collecting sinking materials for the purpose of recycling the same. Accordingly, much of the sinking material, which could be recycled to provide improved yields of product, is lost.